California's corporate farms are guzzling a disproportionate share of subsidized federal water, a new study concludes.

The report by the Environmental Working Group analyzed federal and state records from 2002 to compile a list of the top recipients of subsidized agricultural water from the Central Valley Project, the huge federal water delivery system that supplies roughly one-fifth of the state's domestic and irrigation water - about 7 million acre feet annually.

About 6,800 farms use project water, accounting for about 2.7 million acre feet of the deliveries. Central Valley farmers typically pay a fraction of the cost south state urbanites pay for the federal water.

"What we found is that 10 percent of the farmers are getting about 67 percent of the water," said Bill Walker, the group's West Coast vice president. "Total water subsidies to the farmers top $400 million, when figured in terms of replacement costs on the current water market."

Farmers and irrigation district managers excoriated the methodology used by Environmental Working Group, calling it sloppy and inaccurate. But the nonprofit advocacy organization said it stood by its report, and it said it would correct any errors if confirmed by water district records.

The report found considerable support on Capitol Hill with those fighting a Bush administration move to renew upcoming Central Valley Project contracts with little or no review.

"The report confirms what we've known for many years, that big farms are getting the bulk of these subsidies," said Rep. George Miller, D-Martinez, who sponsored 1992 legislation that diverted some project water from agriculture to environmental restoration. "We now see (Bush) administration attempts to lock in this system well into the century by renewing contracts that were written in the 1950s. It's crazy. You're talking about some of the richest people in the state standing in line for hand-outs."

The Environmental Working Group specializes in compiling databases on environmental and agricultural issues. For this report, although it was able to use government records to identify the agricultural water districts that received the most project water, it could not obtain water district records to verify the individual farms receiving the greatest amounts of project water. This is because of a state law passed in the 1990s allowing water districts to maintain private records.

Instead, it obtained state records of pesticide application licenses issued to individual farms. Using these records, the group was able to identify the acreage each farm planted to specific crops. The group's analysts then extrapolated water use per farm based on the known water requirements of each crop.

Other significant claims in the report include:

-- Twenty-seven farms received water subsidies worth $1 million or more at current water market values.

-- In 2002, project irrigation water was provided to some districts at less than 2 percent of the price paid by Los Angeles residents.

-- The project's irrigation water cost about 13 percent of the price paid by state and local agencies for federal water used to restore San Francisco Bay and the delta of the Sacramento and San Joaquin rivers.

Walker said the Central Valley Project, authorized in 1936, originally was founded to irrigate family farms of no more than 160 acres. The amount of allowable acreage was raised to 960 acres in 1982. But some farmers were able to leverage the amount of federal water they received by subdividing their properties among family members, each of whom received a 960-acre water allotment.

"This is not family farming," Walker said. "This wasn't the intention of the original legislation."

"(Subdivisions) may have occurred in the past, but they are not occurring now," McCracken said. Farmers using federal water to irrigate holdings exceeding the 960-acre, he said, are paying the full cost for that water.

Renee Sharp, a senior analyst for Environmental Working Group, disputed that, saying that some farmers in that circumstance -- "but not most" -- pay full cost.

Using Westlands, the largest water district in the state, as an example, she said if you "take ... the 421 farms it serves, calculate the amount of water the district is getting and what it's paying for it, there's no way those farmers are paying full cost."

Tom Birmingham, the general manager of Westlands, called the report "simplistic and based on erroneous assumptions," and he took particular issue with the report's calculation of subsidy value.

"If EWG's analyses were applied throughout the state, you'd find everyone receives subsidized water," he said. "Every water agency pays a rate based, by law, on the actual costs of delivering water."

That's why Westlands pays more for its water than Central Valley Project beneficiaries in the Sacramento Valley, who pump right from the Sacramento River, Birmingham said.

"We, on the other hand, have to pump it out of the delta and ship it through the aqueduct," he said. "Los Angeles pays more than we do because it has to be shipped past us, pumped over the Tehachapis and treated to make it potable. That adds further expense."